Language is the remarkable faculty by which humans convey thoughts to one another by means of a highly structured signal. Language works by two principles: a dictionary of memorized symbols, that is, words, and a set of generative rules organized into several subsystems, that is, grammar. The machinery of language appears to have been designed to encode and decode propositional information for the purpose of sharing it with others. Language is universally complex and develops reliably throughout the species, partly independently of general intelligence. I suggest that language is an adaptation for sharing information. It fits with many other features of our zoologically distinctive 'informavore' niche, in which people acquire, share and apply knowledge of how the world works to outsmart plants, animals and each other.

Adaptation, Psychological↗

PubMed1995

German inflection: the exception that proves the rule.

Language is often explained as the product of generative rules and a memorized lexicon. For example, most English verbs take a regular past tense suffix (ask-asked), which is applied to new verbs (faxed, wugged), suggesting the mental rule "add -ed to a Verb." Irregular verbs (break-broke, go-went) would be listed in memory. Alternatively, a pattern associator memory (such as a connectionist network) might record all past tense forms and generalize to new ones by similarity; irregular and regular patterns would differ only because of their different numbers of verbs. We present evidence that mental rules are indispensible. A rule concatenates a suffix to a symbol for verbs, so it does not require access to memorized verbs or their sound patterns, but applies as the "default," whenever memory access fails. We find 21 such circumstances for regular past tense formation, including novel, unusual-sounding, and rootless and headless derived words; in every case, people inflect them regularly (explaining quirks like flied out, sabre-tooths, walkmans). Contrary to the connectionist account, these effects are not due to regular words constituting a large majority of vocabulary. The German participle -t applies to a much smaller percentage of verbs than its English counterpart, and the German plural -s applies to a small minority of nouns. But the affixes behave in the language like their English counterparts, as defaults. We corroborate this effect in two experiments eliciting ratings of participle and plural forms of novel German words. Thus default suffixation is not due to numerous regular words reinforcing a pattern in associative memory. Because default cases do not occupy a cohesive similarity space, but do correspond to the range of a symbol, they are evidence for a memory-independent, symbol-concatenating mental operation.

Adult↗

PubMed1995

Weird past tense forms.

It is often assumed that children go through a stage in which they systematically overapply irregular past tense patterns to inappropriate verbs, as in wipe-wope, bring-brang, trick-truck, walk-has walken. Such errors have been interpreted both as reflecting over-use of minor grammatical rules (e.g. 'change i to a'), and as reflecting the operation of a connectionist pattern associator network that superimposes and blends patterns of various degrees of generality. But the actual rate, time course, and nature of these errors have never been documented. We analysed 20,000 past tense and participle usages from nine children in the CHILDES database, looking for overapplications of irregular vowel-change patterns, as in brang, blends, as in branged, productive suffixations of -en, as in walken, gross distortions, as in mail-membled, and double-suffixation, as in walkeded. These errors were collectively quite rare; children made them in about two tenths of one per cent of the opportunities, and with few stable patterns: the errors were not predominantly word-substitutions, did not occur predominantly with irregular stems, showed no consistency across verbs or ages, and showed no clear age trend. Most (though not all) of the errors were based closely on existing irregular verbs; gross distortions never occurred. We suggest that both rule-theories and connectionist theories have tended to overestimate the predominance of such errors. Children master irregular forms quite accurately, presumably because irregular forms are just a special case of the arbitrary sound-meaning pairings that define words, and because children are good at learning words.

Child↗

PubMed1994

The representation of location in visual images.

By definition, visual image representations are organized around spatial properties. However, we know very little about how these representations use information about location, one of the most important spatial properties. Three experiments explored how location information is incorporated into image representations. All of these experiments used a mental rotation task in which the location of the stimulus varied from trial to trial. If images are location-specific, these changes should affect the way images are used. The effects from image representations were separated from those of general spatial attention mechanisms by comparing performance with and without advance knowledge of the stimulus shape. With shape information, subjects could use an image as a template, and they recognized the stimulus more quickly when it was at the same location as the image. Experiment 1 demonstrated that subjects were able to use visual image representations effectively without knowing where the stimulus would appear, but left open the possibility that image location must be adjusted before use. In Experiment 2, distance between the stimulus location and the image location was varied systematically, and response time increased with distance. Therefore image representations appear to be location-specific, though the represented location can be adjusted easily. In Experiment 3, a saccade was introduced between the image cue and the test stimulus, in order to test whether subjects responded more quickly when the test stimulus appeared at the same retinotopic location or same spatiotopic location as the cue. The results suggest that location is coded retinotopically in image representations. This finding has implications not only for visual imagery but also for visual processing in general, because it suggests that there is no spatiotopic transform in the early stages of visual processing.

Adolescent↗

PubMed1994

Sensitivity of children's inflection to grammatical structure.

What is the input to the mental system that computes inflected forms like walked, came, dogs, and men? Recent connectionist models feed a word's phonological features into a single network, allowing it to generalize both regular and irregular phonological patterns, like stop-stopped, step-stepped and fling-flung, cling-clung. But for adults, phonological input is insufficient: verbs derived from nouns like ring the city always have regular past tense forms (ringed), even if they are phonologically identical to irregular verbs (ring the bell). Similarly, nouns based on names, like two Mickey Mouses, and compounds based on possessing rather than being their root morpheme, such as two sabertooths, take regular plurals, even when they are homophonous with irregular nouns like mice and teeth. In four experiments, testing 70 three- to ten-year-old children, we found that children are sensitive to such nonphonological information: they were more likely to produce regular inflected forms for forms like to ring ('to put a ring on') and snaggletooth (a kind of animal doll with big teeth) than for their homophonous irregular counterparts, even when these counterparts were also extended in meaning. Children's inflectional systems thus seem to be like adults': irregular forms are tied to the lexicon but regular forms are computed by a default rule, and words are represented as morphological tree structures reflecting their derivation from basic word roots. Such structures, which determine how novel complex words are derived and interpreted, also govern whether words with irregular sound patterns will be regularized: a word can be irregular only if its structure contains an irregular root in 'head' position, allowing the lexically stored irregular information to percolate up to apply to the word as a whole. In all other cases, the inflected form is compouted by a default regular rule. This proposal fits the facts better than alternatives appealing to ambiguity reduction or semantic similarity to a word's central sense. The results, together with an analysis of adult speech to children, suggest that morphological structure and a distinction between mechanisms for regular and irregular inflection may be inherent to the design of children's language systems.

Child↗

PubMed1992

Overregularization in language acquisition.

Children extend regular grammatical patterns to irregular words, resulting in overregularizations like comed, often after a period of correct performance ("U-shaped development"). The errors seem paradigmatic of rule use, hence bear on central issues in the psychology of rules: how creative rule application interacts with memorized exceptions in development, how overgeneral rules are unlearned in the absence of parental feedback, and whether cognitive processes involve explicit rules or parallel distributed processing (connectionist) networks. We remedy the lack of quantitative data on overregularization by analyzing 11,521 irregular past tense utterances in the spontaneous speech of 83 children. Our findings are as follows. (1) Overregularization errors are relatively rare (median 2.5% of irregular past tense forms), suggesting that there is no qualitative defect in children's grammars that must be unlearned. (2) Overregularization occurs at a roughly constant low rate from the 2s into the school-age years, affecting most irregular verbs. (3) Although overregularization errors never predominate, one aspect of their purported U-shaped development was confirmed quantitatively: an extended period of correct performance precedes the first error. (4) Overregularization does not correlate with increases in the number or proportion of regular verbs in parental speech, children's speech, or children's vocabularies. Thus, the traditional account in which memory operates before rules cannot be replaced by a connectionist alternative in which a single network displays rotelike or rulelike behavior in response to changes in input statistics. (5) Overregularizations first appear when children begin to mark regular verbs for tense reliably (i.e., when they stop saying Yesterday I walk). (6) The more often a parent uses an irregular form, the less often the child overregularizes it. (7) Verbs are protected from overregularization by similar-sounding irregulars, but they are not attracted to overregularization by similar-sounding regulars, suggesting that irregular patterns are stored in an associative memory with connectionist properties, but that regulars are not. We propose a simple explanation. Children, like adults, mark tense using memory (for irregulars) and an affixation rule that can generate a regular past tense form for any verb. Retrieval of an irregular blocks the rule, but children's memory traces are not strong enough to guarantee perfect retrieval. When retrieval fails, the rule is applied, and overregularization results.

Age Factors↗

PubMed1991

Rules of language.

Language and cognition have been explained as the products of a homogeneous associative memory structure or alternatively, of a set of genetically determined computational modules in which rules manipulate symbolic representations. Intensive study of one phenomenon of English grammar and how it is processed and acquired suggest that both theories are partly right. Regular verbs (walk-walked) are computed by a suffixation rule in a neural system for grammatical processing; irregular verbs (run-ran) are retrieved from an associative memory.

Aphasia↗

PubMed1991

Introduction to special issue of Cognition on lexical and conceptual semantics.

It is the fate of those who dwell at the lower employments of life, to be rather driven by the fear of evil, than attracted by the prospect of good; to be exposed to censure, without hope of praise; to be disgraced by miscarriage, or punished for neglect, where success would have been without applause, and diligence without reward. Among these unhappy mortals is the writer of dictionaries ... (Preface, Samuel Johnson's Dictionary, 1755).

Cognition↗

PubMed1991

Affectedness and direct objects: the role of lexical semantics in the acquisition of verb argument structure.

How do speakers predict the syntax of a verb from its meaning? Traditional theories posit that syntactically relevant information about semantic arguments consists of a list of thematic roles like "agent", "theme", and "goal", which are linked onto a hierarchy of grammatical positions like subject, object and oblique object. For verbs involving motion, the entity caused to move is defined as the "theme" or "patient" and linked to the object. However, this fails for many common verbs, as in fill water into the glass and cover a sheet onto the bed. In more recent theories verbs' meanings are multidimensional structures in which the motions, changes, and other events can be represented in separate but connected substructures; linking rules are sensitive to the position of an argument in a particular configuration. The verb's object would be linked not to the moving entity but to the argument specified as "affected" or caused to change as the main event in the verb's meaning. The change can either be one of location, resulting from motion in a particular manner, or of state, resulting from accommodating or reacting to a substance. For example, pour specifies how a substance moves (downward in a stream), so its substance argument is the object (pour the water/glass); fill specifies how a container changes (from not full to full), so its stationary container argument is the object (fill the glass/water). The newer theory was tested in three experiments. Children aged 3;4-9;4 and adults were taught made-up verbs, presented in a neutral syntactic context (this is mooping), referring to a transfer of items to a surface or container. Subjects were tested on their willingness to encode the moving items or the surface as the verb's object. For verbs where the items moved in a particular manner (e.g., zig-zagging), people were more likely to express the moving items as the object; for verbs where the surface changed state (e.g., shape, color, or fullness), people were more likely to express the surface as the object. This confirms that speakers are not confined to labeling moving entities as "themes" or "patients" and linking them to the grammatical object; when a stationary entity undergoes a state change as the result of a motion, it can be represented as the main affected argument and thereby linked to the grammatical object instead.

Attention↗

PubMed1991

Syntax and semantics in the acquisition of locative verbs.

Children between the ages of three and seven occasionally make errors with locative verbs like pour and fill, such as *I filled water into the glass and *I poured the glass with water (Bowerman, 1982). To account for this pattern of errors, and for how they are eventually unlearned, we propose that children use a universal linking rule called object affectedness: the direct object corresponds to the argument that is specified as 'affected' in some particular way in the semantic representation of a verb. However, children must learn which verbs specify which of their arguments as being affected; specifically, whether it is the argument whose referent is undergoing a change of location, such as the content argument of pour, or the argument whose referent is undergoing a change of state, such as the container argument of fill. This predicts that syntactic errors should be associated with specific kinds of misinterpretations of verb meaning. Two experiments were performed on the ability of children and adults to understand and produce locative verbs. The results confirm that children tend to make syntactic errors with sentences containing fill and empty, encoding the content argument as direct object (e.g. fill the water). As predicted, children also misinterpreted the meanings of fill and empty as requiring not only that the container be brought into a full or empty state, but also that the content move in some specific manner (by pouring, or by dumping). Furthermore, children who misinterpreted the verbs' meanings were more likely to make syntactic errors with them. These findings support the hypothesis that verb meaning and syntax are linked in precise ways in the lexicons of language learners.

Child↗